A plurality of fields and endeavors practice combining a gas stream with a liquid. Devices used for the dispersion of gas into a liquid include ejectors, venturi injectors, slot injectors, jet mixers and jet aerators and other gas liquid mixers. Such gas transfer devices have found widespread use in a variety of fields including those of wastewater treatment and fermentation.
Ejectors can move gas into a liquid with or without the aid of a fan or blower. The liquid spray coming from a nozzle in the ejector creates a pressure drop due to the Bernoulli effect. This pressure drop can be used to move gas through the ejector. Ejectors can be used to introduce an oxygen-containing gas such as air into a liquid with high gas transfer and energy efficiency, and they are typically installed at or near the bottom of a reactor (which may be a tank, basin or other natural or man-made container) containing the liquid to receive gas injection.
Ejectors are applied across a wide range of liquid treatment applications. Their primary purpose is to transfer gas to the liquid. For example, in wastewater treatment, biological reactors are provided with a combination of mixing and/or aeration devices that are used to transfer oxygen into wastewater. Ejectors are often used in these applications because they can provide independent control of oxygen transfer and mixing with the same device.
Ejectors have typically either been attached to piping systems using intermediate pipes to deliver liquid and gas from generic distribution piping to the independent ejector, or distribution piping has been fabricated integrally with ejectors, injectors or other gas transfer devices. These configurations are either bulky or do not allow for the removal of the devices for inspection, cleaning or replacement. The use of feed pipes creates additional head loss and additional opportunity for fouling. Systems with fixed gas transfer devices cannot be readily cleaned, replaced or repaired.
Schulte et al. U.S. Pat. No. 4,098,851 discloses a device for mixing gases and liquids which is said to have an intense mixing effect and be very easy to clean. The device comprises a housing with feed pipes for gas and liquid. An injector nozzle is inserted into the housing, and a mixing nozzle is screwed in the housing.
Zlokarnik et al. U.S. Pat. No. 4,162,970 discloses an injector for the dispersion of a gas into a liquid and comprising a gas inlet, a liquid inlet, and a mixing chamber communicating with said inlets and having an inlet and an outlet. The inlet of the mixing chamber is substantially round in cross-section and the outlet is substantially slit-shaped.
Zlokarnik et al. U.S. Pat. No. 4,162,971 discloses an injector for the dispersion of a gas into a liquid and comprising a gas inlet, a liquid inlet, and a mixing chamber communicating with said inlets and having an inlet and an outlet. At least one deflecting element is disposed in the mixing chamber along the axis of the liquid inlet, whereby the liquid is distributed across the full cross-section of the mixing chamber.